Sorption on natural solids for arsenic removal

Steady state experiments were conducted on arsenic sorption from aqueous so lutions by natural solids to test the feasibility of these materials to act as concentrator for arsenic removal from groundwater and drinking water. T he solids considered were natural zeolites, volcanic stone, and the cactace ous powder CACMM. The arsenic species studied were As(III), As(V), dimethyl arsinic acid (DMA) and phenylarsonic acid (PHA). The arsenic removed was de termined from the data obtained by measuring the concentration diminution o f the arsenic species in the liquid phase at equilibrium before and after t he adsorption experiment by means of ICP-AES for the total concentration of arsenic and IC-ICP-MS to determine the arsenic species. The latter method allowed the detection of As(V) additionally formed as a result of the oxida tion of As(III) on some of the zeolites. The sorption of the arsenic specie s onto zeolites was studied on both non-activated and activated zeolites, a s well as on zeolites hydrogenated or modified with iron, and with respect to varying pH. The kinetics and the ability to desorb and readsorb the arse nic species were investigated for selected zeolites. (C) 2001 Elsevier Scie nce B.V. All rights reserved.